filter_input

west {:a7} jsausa {:d0t}~ com (2012-11-28 20:30:36)

It's worth noting that the names for variables in filter input obey the same rules as variable naming in PHP (must start with an underscore or letter). We were allowing users to build custom forms but hashing the names to prevent them from putting arbitrary content into the dom. Turns out the hash function occasionally produced entirely numeric values for the field name... which doesn't work with filter_input but worked fine if you read directly from $_GET, $_POST, or $_REQUEST. A workaround is to always prefix an underscore to the field name.

chris at chlab dot ch (2012-03-20 09:46:44)

To use a class method for a callback function, as usual, provide an array with an instance of the class and the method name.
Example:

<?php
class myValidator
{
  public function username($value)
  {
    // return username or boolean false
  }
}

$myValidator = new myValidator;
$options = array('options' => array($myValidator, 'username'));
$username = filter_input(INPUT_GET, 'username', FILTER_CALLBACK, $options);
var_dump($username);
?>

ss23 at ss23 dot geek dot nz (2010-07-28 23:37:52)

Note that this function doesn't (or at least doesn't seem to) actually filter based on the current values of $_GET etc. Instead, it seems to filter based off the original values.
<?php
$_GET['search'] = 'foo'; // This has no effect on the filter_input

$search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);
$search_url = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_ENCODED);
echo "You have searched for $search_html.\n";
echo "<a href='?search=$search_url'>Search again.</a>";
?>

If you need to set a default input value and filter that, use filter_var on your required input variable instead

travismowens at gmail dot com (2010-07-28 09:21:32)

I wouldn't recommend people use this function to store their data in a database. It's best not to encode data when storing it, it's better to store it raw and convert in upon the time of need.
One main reason for this is because if you have a short CHAR(16) field and the text contains encoded characters (quotes, ampersand) you can easily take a 12 character entry which obviously fits, but because of encoding it no longer fits.
Also, while not as common, if you need to use this data in another place, such as a non webpage (perhaps in a desktop app, or to a cell phone SMS or to a pager) the HTML encoded data will appear raw, and now you have to decode the data.
In summary, the best way to architect your system, is to store data as raw, and encode it only the moment you need to. So this means in your PHP upon doing a SQL query, instead of merely doing an echo $row['title'] you need to run htmlentities() on your echos, or better yet, an abstract function.

med dot k1987 at yahoo dot com (2010-06-30 07:48:38)

Hello,
Does anybody know how to prevent FILTER_SANITIZE_SPECIAL_CHARS from converting the line breaks (\n) into (
).
I'm developing a simple commenting system for my website and I found that the php filter converts \n to 
 so when using nl2br() there are no line breaks.
help please.
thanks :)

Maksym Karazeev (2009-03-03 13:13:43)

Just a tip. 

Note how to setup default filter for filter_var_array

When I tried to use filter_var_array and didn't mentioned all array indexes in definition it filtered it with some filter and broke values so using this tip corrected everything

<?php
$def = array_map(create_function('', 'return array("filter"=>FILTER_UNSAFE_RAW);'), $input);
?>

Marques Johansson (2008-01-02 11:30:04)

Despite the documentation for 'type', you can specify multiple types by doing:
$test = filter_input(INPUT_GET | INPUT_POST, 'test');
This was tested in 5.2.3.
When both are set it appears to return the value defined first by variables_order (php.ini).
This trick does not seem to work in filter_input_array though. Neither function supports INPUT_REQUEST at the moment.

vid at phpcult dot com (2007-12-10 00:49:41)

If you want to use the callback filter with filter_input, you need to do something like:
$args = array ('options' => 'mycallbackfunction');
$foobar = filter_input(INPUT_POST,'postedvariable',FILTER_CALLBACK,$args);

anthony dot parsons at manx dot net (2007-08-23 14:10:24)

FastCGI seems to cause strange side-effects with unexpected null values when using INPUT_SERVER and INPUT_ENV with this function. You can use this code to see if it affects your server:
<?php
var_dump($_SERVER);
foreach ( array_keys($_SERVER) as $b ) {
    var_dump($b, filter_input(INPUT_SERVER, $b));
}
echo '<hr>';
var_dump($_ENV);
foreach ( array_keys($_ENV) as $b ) {
    var_dump($b, filter_input(INPUT_ENV, $b));
}
?>
If you want to be on the safe side, using the superglobal $_SERVER and $_ENV variables will always work. You can still use the filter_* functions for Get/Post/Cookie without a problem, which is the important part!